1. Field of the Invention
The present invention relates to novel ampholyte polymers, polymer compositions and methods for using such polymers and compositions in personal care applications. In general terms, the polymers and polymer compositions of the present invention are believed to be useful in the treatment of keratin-containing substrates. Keratin substrates include, but are not limited to, animal and human hair, skin and nails.
More particularly, the instant invention relates to polymer compositions and methods for treating keratin in which a cosmetically acceptable medium is used which contains at least about 0.01% by weight of an ampholyte polymer comprising acrylamidopropyltrimethyl ammonium chloride or methacrylamido-propyltrimethyl ammonium chloride; acrylic acid, methacrylic acid, 2-acrylamido-2-methylpropanol sulfonic acid or 2-methacrylamido-2-methylpropane sulfonic acid; and, optionally, an alkyl (meth)acrylate. Preferably, the cosmetically acceptable medium is a hair care product such as a shampoo, conditioner, styling product or rinse, or a skin care product such as a cleaner, lotion or cream.
The surface properties of keratin are of interest in cosmetic science, and there has been a long-standing desire to discover ingredients which will beneficially affect the topical and bulk condition of keratinous substrates, such as hair. For example, such ingredients must have adequate adherent properties, so that they are not only adsorbed initially, but are also retained on exposure to water. This property is referred to as "substantivity", i.e., the ability of a material to be adsorbed onto keratin and to resist removal by water rinse-off.
Hair is composed of keratin, a sulfur-containing fibrous protein. The isoelectric point of keratin, and more specifically of hair, is generally in the pH range of 3.2-4.0. Therefore, at the pH of a typical shampoo, hair carries a net negative charge. Consequently, cationic polymers have long been used as conditioners in shampoo formulations, or as a separate treatment, in order to improve the wet and dry combability of the hair. The substantivity of the cationic polymers for negatively charged hair along with film formation facilitates detangling during wet hair combing and a reduction in static flyaway during dry hair combing. Cationic polymers generally also impart softness and suppleness to hair.
When cationic polymers are added to shampoos (or to skin care products such as cleaning compositions)containing anionic surfactants, formation of highly surface active association complexes generally takes place, which imparts improved foam stability to the shampoo. Maximum surface activity and foam stability, or lather, are achieved at near stoichiometric ratios of anionic surfactant: cationic polymer, where the complex is least water soluble. Generally, cationic conditioners exhibit some incompatibility at these ratios. Compatibility gives a commercially more desirable clear formulation, while incompatibility leads to a haze or precipitation, which is aesthetically less desirable in some formulations.
Hair fixative properties such as curl retention are believed to be directly related to film forming properties of cationic polymers, as well as to molecular weight, with performance generally increasing with increasing molecular weight. However, the fixative properties conferred by cationic polymers generally tend to have a reciprocal relationship to other conditioning properties, i.e., good curl retention usually means that properties such as wet compatibility will suffer, and vice versa.
Surprisingly, it has been found that the instant ampholyte polymers, which comprise: a) acrylamidopropyltrimethyl ammonium chloride (APTAC) or methacrylamidopropyltrimethyl ammonium chloride (MAPTAC); b) acrylic acid (AA), methacrylic acid (MM), 2-acrylamido-2-methylpropane sulfonic acid (AMPSA) or 2-methacrylamido-2-methylpropane sulfonic acid (MAMPSA); and c) optionally, a C.sub.1 -C.sub.22 straight or branched alkyl acrylate or methacrylate; are generally useful in cosmetic formulations and provide particularly improved conditioning properties to hair products. Aside from improved conditioning, as measured by combability, substantivity, flyaway and/or feel, these polymers at the same time may improve, but are generally not detrimental to, hair fixative properties such as curl retention.
In a preferred embodiment of the present invention, an effective amount of an ampholyte polymer containing AA, MAPTAC and methyl acrylate moieties is added to an anionic surfactant-containing hair or skin care product, preferably a hair care product. Thus, the polymer compositions of the present invention can be used in, inter alia, shampoos, conditioners, rinses, coloring products, bleaching products, setting lotions, blow-drying lotions, restructuring lotions, perms and straightening products.
Aside from hair care uses, skin and nail conditioning products are desired which function to improve properties such as retention of moisture, softening of the skin, attraction of air moisture, retardation of water loss, feel and reduction of skin irritations caused by contact with cosmetic ingredients. Examples of such products include detergents, lotions and soaps.
Generally, two broad areas of skin care products have been recognized as skin conditioners: emollients and humectants. Emollients generally provide improved moisture retention in the skin and plasticization/softening of the skin. Common commercial emollients are mineral oil; petrolatum; aliphatic alcohols, such as stearyl alcohol; lanolin and its derivatives; glycol stearate; and fatty acids, such as triethanolamine oleate. Humectants generally attract moisture, retard evaporation of water from the skin surface, and plasticize/soften skin. Common commercial humectants include glycerin, propylene glycol, sorbitols, and polyethylene glycols.
A desirable skin conditioner should impart at least some of the attributes of an emollient or a humectant, as well as provide improved lubricity and feel to the skin after treatment and/or reduce skin irritation caused by other components in the conditioner such as, for example, soaps, detergents, foam boosters, surfactants, and perfumes. It is known by those skilled in the art that cationic polymers may be employed as skin and nail conditioners.
At times, it is also desirable that the ingredients of skin and nail care products have adequate adherent properties, so that they are not only adsorbed initially, but are also retained on exposure to water. This property, as in hair care applications, is referred to as "substantivity", i.e., the ability of a material contacted with the keratin of skin or nails to resist removal by water rinse-off. Generally, pH's typical of use conditions, skin and nails carry a net negative charge. Consequently, cationic polymers have long been used as conditioners in nail and skin care formulations. The substantivity of the cationic polymers for negatively charged skin and nails leads to film formation that facilitates lubricity, moisturizing and feel. Two commercially used cationic polymers are Merquat.RTM. 550 (Commercially available from Calgon Corporation), a copolymer of acrylamide and dimethyldiallylammonium chloride, and Polymer JR.RTM. (Commercially available for Union Carbide), a quaternary nitrogen-containing hydroxyethyl cellulose.
The skin and nail conditioning properties of lubricity, moisturizing and feel, are related to the film forming properties of the cationic monomers, as well as to molecular weight, with performance generally increasing with increasing molecular weight.
The conditioning property improvements of the instant polymers and polymer compositions are believed to be applicable to skin and nail care products. Further, It will be appreciated that fragile or brittle nails may be strengthened or hardened, and the appearance of the nails improved, as a result of the use of the instant ampholyte polymers.
2. Brief Description of the Background Art
Keratin conditioning additives generally are of three primary types: cationic polymers, proteins or protein derivatives, and fatty quaternary ammonium compounds. Commonly used cationic polymers include: quaternary nitrogen-containing hydroxyethyl cellulose compounds, copolymers of vinylpyrrolidone and dimethylamino-ethylmethacrylate, and amino functional polydimethyl-siloxane. Hydrolyzed animal protein has been frequently used as a keratin conditioner. Also used are natural products such as collagen and casein. Suitable quaternary ammonium compounds include such products as stearyl dimethyl ammonium chloride.
Conditioning additives comprising copolymers of dimethyldiallylammonium chloride and other monomers are well known; see, e.g., EP 308189 (with acrylamide)and EP 0 308 190 and U.S. Pat. No. 4,803,071 (with hydroxyethyl cellulose). The use of such polymers in cosmetics is also described in Sykes et al., Drug Cosmet. Ind., 126(2), 62, 64, 66, 68, 136 (1980). Amphoteric betaines have also been employed in cosmetic compositions; see GB 2, 113, 245 which discloses use of betainized dialkylaminoalkyl(meth)acrylate together with a cationic polymer.
The use of polymers of dimethyldiallylammonium chloride (DMDAAC) in the treatment of keratin is also known. See, e.g., U.S. Pat. No. 4,175,572 and 3,986,825. U.S. Pat. No. 5,296,218 discloses DMDAAC-based ampholyte terpolymers containing acrylamide for hair care applications, while U.S. Pat. No. 5,275,809 discloses DMDAAC-based ampholyte terpolymers containing acrylamidomethylpropyl sulfonic acid for hair care uses.
While the use of various combinations of cationic, anionic and/or nonionic polymers as additives for hair, skin and nail conditioning compositions has been suggested heretofore, there has been no appreciation that a significant improvement in conditioning properties could be obtained by employing an ampholyte polymer of the type described herein.
For example, U.S. Pat. No. 4,859,458 discloses hair conditioning polymers containing alkoxylated nitrogen salts of sulfonic acid which may also include additional monomers that may be neutral, anionic and/or cationic. While these include acrylamide, acrylic acid and dimethyldiallylammonium chloride, there is no suggestion of the ampholyte polymers of the present invention.
EP 0 353 987 discloses polymers for water-rinsable personal care products including conditioning shampoos, comprising a cationic monomer including dimethyldiallylammonium chloride, a monomer that carries a pendant group A.sub.n R where n is 0 or a positive integer, A is ethyleneoxy and R is a hydrocarbyl group of 8 to 30 carbon atoms, and optionally a nonionic and/or an anionic monomer. However, there is no suggestion of the ampholyte terpolymers of the present invention.
U.S. Pat. No. 4,710,374 discloses compositions suitable for treating hair comprising a cationic polymer including poly(dimethyldiallylammonium chloride), and an anionic latex, but there is no suggestion of the ampholyte terpolymers of the present invention.
U.S. Pat. No. 4,842,849 discloses compositions suitable for treating keratin comprising at least one cationic polymer including poly(dimethyldiallylammonium chloride), and at least one anionic polymer containing vinylsulfonic groups, optionally copolymerized with acrylamide. The cationic polymer may be an amphoteric polymer as defined, but none of these combinations suggest the ampholyte terpolymers of the present invention.
EP 0 080 976 discloses aqueous hair-cosmetic compositions containing a surface active polymeric acrylic-based quaternary ammonium salt, a monomeric or oligomeric ammonium salt, and a surface active nonionic, anionic or zwitterionic component. The ampholyte polymers of the present invention are not suggested.
DE 4401 708 A1 discloses the use of low molecule weight MAPTAC/acrylic acid polymers in cosmetic applications. The high molecular weight (i.e., greater than 100,000) polymers of the instant invention are not disclosed or suggested.
U.S. Pat. No. 4,128,631 discloses a method of imparting lubricity to keratinous substrates such as skin or hair by contacting said substrates with a salt of 2-acrylamido-2-methylpropane sulfonic acid (AMPSA) having a molecular weight of from 1-5 million. See also U.S. Pat. No. 4,065,422. The ampholyte polymers of the present invention and their unexpected advantageous properties are not suggested.
The ampholyte polymers of the present invention and compositions containing such polymers are novel because of their unique structure, molecular weight, conditioning properties, and their general advancement of the state of the keratin conditioning art. The polymers of the present invention afford conditioning properties which are a surprising improvement over those possessed by the keratin conditioning additives in the prior art described above. Thus, for hair care, properties such as detangling, wet compatibility, wet feel, dry feel, sheen, static flyaway control, and/or curl retention are improved while, for skin and nail care, properties such strength and appearance, retention of skin moisture, softening of the skin, attraction of air moisture, retardation of skin water loss and/or, feel and reduction of skin irritations caused by contact with detergents, soaps and the like are improved.